All around are palm trees and shimmering blue sea. It's inevitable, therefore, that spirits should sag, for there you are tethered to your in-tray while postcards from colleagues in exotic climes multiply round your lonely desk.

August ennui is a debilitating affliction that can set in during the summer holiday season. Symptoms appear when colleagues and clients are prostrate on beach loungers, while those left behind toil on amid the empty desks.

"For some reason, work seems more purposeful when there are a lot of people buzzing around you," says Cary Cooper, professor of organisational psychology and health at Lancaster University Management School. "Work meets our social as well as financial needs, and in a half-empty office you are less hyped up – that can be de-energising."

This apathy is made worse by the fact the pace of work is often slower during summer, when customers and clients are themselves on leave, and without pressing deadlines to galvanise resolve, it can be hard to maintain momentum.

"There's the feeling that everyone else is doing something exciting and you're just treading water," says Julianne Miles, a chartered psychologist and founder of the career management consultancy Career Psychologists.

In fact, this lull is an opportunity to consolidate your position in the workplace. Summer, in the employment world, is the best season to start on a little spring cleaning, so bin those taunting postcards and seize the moment while your colleagues' backs are turned with this 10-step guide.

Expand horizons

Ask yourself what aspects of your job you most enjoy, then work out how you can expand on these, Miles suggests. Covering for an absent colleague might give you the chance to get involved in new projects that play to your strengths and keep the adrenaline flowing.

Corinne Mills, managing director of the career coaching agency Personal Career Management, says: "It's a great time to be nosy. When colleagues are not there protecting their territory or trying to block you, you can take on some of their role.

"Ask them before they go if they would like you to help with anything. Answer their phone and instead of asking the caller to ring back, try to get involved. Your manager will be thrilled if you deal with things during their absence."

Make your voice heard

"When the foot is off the pedal there is more time for casual chats and all sorts of important things can come out of these," Mills says. You could suggest ideas, volunteer for projects or request favours without being upstaged by louder rivals. "Get the boss to notice you when there is less competition," she advises.

Start networking

"We tend to get ourselves into a rut and rely on the same small set of people at work," Cooper says. "If those people are away, use the phone, Skype or the water cooler to get to know colleagues that you know less well."

He also suggests arranging lunch with clients or suppliers that you deal with but rarely meet. "Eyeball to eyeball contact with people will get you out of the office, stimulate you and could lead to better business," he says.

Get out

Don't spend lunchtime hunched at your desk over Twitter. Twenty minutes of exercise can dissolve office apathy. Go down the high street to buy your sandwich or take a walk round the block. Miles suggests inviting colleagues out for an impromptu picnic.

Get organised

Set yourself small, step-by-step goals that are challenging but achievable, Miles suggests. "Don't try to clear out your entire office in a day, but aim to do, say, one drawer." This is the moment to tackle things that have been at the bottom of your to do list. Write down targets, promise yourself a reward, tick them off as you accomplish them and revel in the resulting sense of virtue.

Feed your mind

If things are quiet, take yourself off to the sort of event, conference or exhibition you are usually too busy to attend. This could make you new contacts, refresh your spirits and expand your expertise.

Start volunteering

Yes, it may sound trite, but helping others – be it a needy workmate or the dispossessed – can lift the spirits and enhance your skills and reputation.

If you have spare time, ask if there is anyone in the office who needs a hand, or find suitable charitable work on the national volunteering database. If it works out you could suggest that your employer adopts the charity and arranges for staff to volunteer once a week.

Assess your objectives

Most of us, Mills says, leave our preparations for personal appraisals until the last minute, when it would be better to devote weeks to working out who we are and why we are here. Take advantage of any downtime to reflect on how things are going.

Break the routine

If you work flexibly, clock in earlier so you have time to take up a new interest after you've put in the hours. Walk to the office a different way, revamp your desk, visit a gallery in your lunch hour: "Anything to stop the feeling that you're on a treadmill," Miles says.

Take comfort in schadenfreude

One aspect of the summer break that has been prolifically researched is the psychological effect of holidays. Opinion seems united in the fact that the preparations involved in taking leave from work and the stress of returning to mountainous in-trays can outweigh the benefits of the break.

While you sit content behind your spring-cleaned desk, revelling in your expanded contact book and masterful project management, your colleagues will return tanned and toned to face their backlog.